Driving out master pin

I just looked at my 7U D4 (late) and it has a solid plug-

I have used a 5/8" slow thread bolt as a puller on on a bigger machine. All of the threaded ones I have done have been fine thread. Take a bottoming tap with you to clean the threads so you can get as much contact area as you can.

On the D2's it is a 3/8" fine thread. You may fine a cork pushed into the hole to keep dirt out. I put a short 1/2" bolt in to keep dirt out.

Kevin

If you have one of the older types that have tapered plugs in 'em, small plug one end and larger plug in the other end you might need a gas ax. I've had a couple of D2's that had that style and while driving the small plug in took a few whacks, trying to drive the larger plug out just didn't work. .had'ta cut the master pins. I didn't realize that Cat used that style on the D4's. .but then what do I know?😆

With the threaded plugs I've had good luck taking 'em out using an impact wrench. Somewhere in my tool box I've got an old socket that's just over the size of the plugs in the inside. .plus a washer I cut out of 1/4" plate. Have a couple of long enough bolts on hand. .I usually use a fresh grade 8 bolt for each plug. Also, heating the plug and letting it cool again after it's been cleaned seems to help.

Any time I break the tracks on anything, I have brand new master pins on hand before I ever start. Much easier to have 'em and maybe not need 'em than to need 'em and not have 'em. .'sides, if I don't use 'em that time there's always the next time.

Good call on the bottom hole tap. Any conformation on a D4 being 3/8" or 1/2" or even a 5/8" bolt? not sure I have bottom hole taps for all the common sizes from 3/8 up to 5/8.

If i cant get the pin out is the next method to cut the mater pin and then carefully cut the center out of the parts left in the chain flange bores being careful not to damage the link?

After a few years of trying to drive out master pins and save them etc, I realized that it is the pin with most wear due to not being counterbored. I then decided it was much easier and also time saving to buy new pins and just gouge the ends of the old pins to relieve the tension, and just tap them out with a small hammer. Installed the new pin easily as I always kept them in 'The Dragon Lady's' deep freeze and greased the links before installing. This worked well on the older D6's and D8H's I had prior to the advent of the split links.

For putting the tracks back together again, I use a slave pin that's about .015" under the size of the master pin. Once I've got that in, I drive the master pin in while at the same time it's pushing the slave pin out. Chilling the master pin and heating the end of the outside link a bit makes life a bit easier.

Ol' Grump - what material do you make the slave pin out of?
Cheers,
Neil.

I made the last one for D4's out of a chunk of mild steel. If I were going to go into the track business, I'd probably opt for some 4130 or 4140. As I only do this every few years, the mild steel holds up fine. If you're going to make one, remember to put a fairly large 45° chamfer on the ends. .say 1/4" or so.

found these and thought i would pass along